This Standard specifies the signalling protocol for the support
of the Make Call Request supplementary service (SS-MCR) at the
Q reference point between Private Integrated services Network
eXchanges (PINXs) connected together within a Private Integrated
Services Network (PISN).

Supplementary service MCR enables a Requesting User to request
a Co-operating User to establish a new Requested Call to a Destination
User. This new Requested Call between the Co-operating and Destination
User can be either a Basic call or a Call Independent Signalling
Connection.

Service specifications are produced in three stages and according
to the method specified in ETS 300 387. This Standard contains
the stage 3 specification for the Q reference point and satisfies
the requirements identified by the stage 1 and stage 2 specifications
in ECMA-343.

The signalling protocol for SS-MCR operates on top of the signalling
protocol for basic circuit switched call control, as specified
in ECMA-143, and uses certain aspects
of the generic procedures for the control of supplementary services
specified in ECMA-165.

This Standard also specifies additional signalling protocol requirements
for the support of interactions at the Q reference point between
SS-MCR and other supplementary services and ANFs.

This Standard is applicable to PINXs, which can interconnect
to form a PISN.